Effect of cooling on the rectal tone

Area of Science:

• Gastroenterology
• Neuroscience
• Physiology

Background:

• The presence of sensory nerve endings in the rectal wall, particularly cold receptors, remains largely uninvestigated.
• Previous literature has not reported the identification of cold receptors sensitive to temperature in the rectal wall.
• This study addresses the hypothesis that rectal cooling influences rectal wall tone.

Purpose of the Study:

• To investigate the effect of rectal cooling on rectal wall tone.
• To determine if rectal cooling elicits a reflex response.
• To explore the potential of a 'rectal cooling reflex' as a diagnostic tool.

Main Methods:

• Twenty-eight healthy volunteers (18 men, 10 women) participated.
• Rectal wall tone was measured using a barostat system during saline infusion at 30°C and 4°C.
• Tests were repeated after rectal anesthesia with lidocaine to assess reflex mediation.

Main Results:

• Infusion of iced saline (4°C) significantly increased rectal tone (p < 0.05), unlike saline at 30°C.
• The latency of the response was measured at a mean of 15.3 ± 1.2 ms.
• Rectal anesthesia abolished the significant change in rectal tone upon iced saline infusion.

Conclusions:

• Rectal infusion of iced saline induces a reflex increase in rectal tone, termed the 'rectal cooling reflex'.
• This reflex is mediated by sensory pathways within the rectal wall.
• The 'rectal cooling reflex' shows potential as a diagnostic tool for rectal motility disorders, pending further research.